1. Field of the Invention
The present invention relates to a fuel cut-off valve that is attached to a fuel tank of an automobile or the like to cause fuel vapor in the fuel tank to escape toward a canister, and inhibits liquid fuel from flowing into the canister.
2. Description of the Related Art
For example, on a fuel tank of an automobile or the like, there is attached a fuel cut-off valve that causes fuel vapor in the fuel tank to escape toward a canister arranged outside the fuel tank, and prevents liquid fuel from discharging to the outside of the fuel tank. The fuel cut-off valve is used not only to prevent outflow of fuel to the outside but also as a fill-up control valve for stopping fuel supply at an upper limit of a fuel supply amount when the fuel is supplied.
Besides a connection pipe that is connected to the canister and is communicated to the outside of the fuel tank, the fuel cut-off valve is sometimes provided with a connection pipe for connecting an evaporation line that couples together other valves such as a pressure control valve and a roll-over valve arranged in the fuel tank.
For example, Japanese Patent Application Laid-open No. 2006-97599 discloses the following fuel cut-off valve. Specifically, the fuel cut-off valve includes a case main body that forms a valve chamber connected to a communication path for communicating the inside of a fuel tank with the outside thereof, a float valve body that is housed in the valve chamber and moves upward and downward while increasing and decreasing a buoyant force with use of fuel in the fuel tank flowing in and out of the valve chamber, to thereby open and close the communication path, fins provided to protrude along an up-down direction of a side wall portion of the float valve body in order to decrease a sliding resistance with respect to an inner peripheral wall surface of a side wall portion of the case main body, a vent hole formed in an upper portion of the side wall portion of the case main body, for ventilating the inside of the fuel tank and the valve chamber.
Further, a case upper portion is fixed by welding to an upper portion of the case main body. On an outer periphery of the case upper portion, a connection pipe communicated to a canister is provided to protrude, and a connection pipe communicated to an evaporation line is provided to protrude. Both of the connection pipes are communicated to each other through an inner periphery of the case upper portion.
In addition, an upper wall portion having a communication hole formed at the center thereof is formed in the upper portion of the case main body. The float valve body floating along with rise of a liquid level of fuel is fitted into the communication hole and closes the communication hole, to thereby inhibit leakage of liquid fuel toward the canister. Further, on an upper surface of the upper wall portion, a rib surrounding the communication hole is provided to protrude from a position with a predetermined gap with respect to the inner periphery of the case upper portion.
In the fuel cut-off valve and a float valve such as a roll-over valve, which are used in the fuel tank, the float valve body closes the communication hole along with the rise of the liquid level of the fuel, to thereby prevent the fuel from leaking to the outside. However, for example, when a vehicle greatly shakes, the fuel sometimes leaks through the communication hole, and leaks into an upper space communicated to the outside.
Therefore, in a case where, besides the connection pipe communicated to the canister, the connection pipe communicated to the evaporation line is coupled to the fuel cut-off valve, the fuel, which enters through the connection pipe on a side of the evaporation line from another valve connected to the evaporation line, sometimes flows into the upper space of the fuel cut-off valve.
In the fuel cut-off valve disclosed in Japanese Patent Application Laid-open No. 2006-97599, the rib surrounding the communication hole is provided on the upper surface of the upper wall portion to protrude from the position with the predetermined gap with respect to the inner periphery of the case upper portion, and hence the fuel leaking through the communication hole of the fuel cut-off valve can be stored within the above-mentioned rib, and can be inhibited from entering the canister.
However, there is a problem in that, when the fuel leaking through another valve enters through the evaporation line, the fuel flows directly into the canister through a space formed outside an outer periphery of the rib. When the liquid fuel flows into the canister, the liquid fuel cannot be handled by the canister, and hence there is a risk in that the fuel flows out to the outside.